The present invention relates to a light-shielding cloth (plush) to be fitted to a photographic film cartridge at its slit for drawing out a film, and further relates to a photographic film cartridge having the plush.
Generally, a photographic film cartridge has a slit (or port) for drawing out a film therethrough, onto the inner surface of which a light-shielding cloth (i.e., plush) is fitted by adhesion. The plush is set in contact with a photographic film so as to keep the film from exposure to light.
FIG. 1 illustrates a section of a representative photographic film cartridge. A photographic film cartridge 10 is a light-shielding case 11 has a slit 14 for drawing out a photographic film 13 which is wound around a spool 12 and placed in the case 11. Inside of the slit 14, a pair of plushes 20a, 20b are fixed by adhesion on its upper and lower surfaces. The plushes 20a, 20b are desired to show good light-shielding property and to be flexible so that they would not give a damage on the photographic film when it is drawn out. The plushes 20a, 20b are also desired to show low resistance in the procedure of drawing out the photographic film. A photographic film cartridge for APS (i.e., Advanced Photo System), however, has no plushes.
The conventional plush is manufactured by the steps of weaving or knitting laminated two woven fabrics or knitted fabrics with pile yarns and sectioning the pile yarns along the interface between the two fabrics (See Japanese Utility Model Publications No. 37-21388 and 61-34526). In the use of thus manufactured plush, a photographic film is shielded from exposure to light by keeping it in contact with the sectioned pile yarns. The sectioned pile yarns have enough flexibility and impart appropriate resistance to the drawn photographic film.
The procedure for weaving or knitting laminated fabrics with pile yarns, however, is performed at low productivity, and hence the cost for manufacturing the conventional plushes is relatively high.
Japanese Patent Provisional Publication No. 7-152114 describes a plush which is manufactured by the steps of raising a surface of a woven fabric and shearing the raised fibers. Japanese Patent Provisional Publication No. 8-15825 describes a plush which is manufactured by the steps of inserting a weft yarn into a warp-knitted fabric and raising the inserted weft yarn.
The plushes manufactured by the procedures described in the above publications shield a photographic film from exposure to light by keeping their raised fibers in contact with the photographic film. Generally, the raising treatment can be conducted at relatively high productivity, as compared with the procedure of weaving or knitting fabrics with pile yarns. Therefore, the raising treatment for manufacture of plushes is advantageous from the viewpoint of production cost.
The step of shearing, however, sometimes imparts to the fiber-raised plush unsatisfactory light-shielding property. If plushes showing unsatisfactory light-shielding property are placed in a photographic film cartridge at its slits, a photographic film encased in the cartridge is apt to expose to light entering through the slits. In order to avoid the exposure problem, it may be considered that a number of raised fibers (hereinafter, this referred to as xe2x80x9craising densityxe2x80x9d) on the plush is increased or a pressure of the raised fibers onto the photographic film is increased. If these measures are adopted, however, it sometimes happen that the photographic film is drawn out with increased resistance and certain difficulty.
Japanese Patent Provisional Publication No. 9-120116 proposes a plush illustrated in FIG. 2 attached hereto. The plush 20 comprises a raised woven, knitted or nonwoven fabric 22 which has raised fibers 21 having a raised height (D1) in the range of 0.5 mm to 1.5 mm. It is stated that a photographic film cartridge equipped with the disclosed plushes gives satisfactorily high resistance to a photographic film in the course of drawing the film, keeping the photographic film from exposure to light.
The above-mentioned plush Tray be manufactured at high productivity and may be advantageous from the viewpoint of production cost.
As a result of study, however, the present inventors have noted that fiber waste produced in the course of the raising treatment or shearing treatment sometimes remain on the plush. The remaining fiber waste is tend to emigrate onto a photosensitive surface of a photographic film when it is drawn out of the film cartridge. Otherwise, the remaining fiber waste is apt to emigrate into a production system for manufacture of a film cartridge and then is transferred onto a photosensitive surface of a photographic film. The photographic film having fiber waste on its photosensitive surface produces a defective photographic image after it is developed. Particularly, if the photographic image is enlarged, the defects are apparently noted.
Accordingly, it is an object of the present invention to provide a plush to be fitted to a photographic film cartridge at its slit through which a photographic film is drawn out, which scarcely produces apparent defects on a photographic image, particularly on an enlarged photographic image.
It is another object of the invention to provide a photographic film cartridge which scarcely produces apparent defects on a photographic image, particularly on an enlarged photographic image.
The present invention resides in a light-shielding cloth (plush) to be fitted to a photographic film cartridge at its slit through which a photographic film is drawn out, which has been subjected to raising treatment and has fiber waste of 30 pieces or less per 1 cm2, preferably 20 pieces or less per 1 cm2, on its surface.
The number of pieces of fiber waste defined above means a number which is determined by the following method:
(1) a plush is placed on a pressure-sensitive adhesive tape (generally called xe2x80x9ccellophane tapexe2x80x9d such as xe2x80x9cCellotapexe2x80x9d available from Nichiban Co., Ltd.) to produce a laminated body;
(2) the laminated body is pressed by means of a press roller (2 kg, width 45 mm, diameter: 95 mm); and
(3) The adhesive tape is peeled off from the plush, and the pieces of fiber waste transferred onto the tape are counted.
Thus counted number corresponds to the number of pieces of fiber waste on the surface of plush which is defined in the invention.
The plush of the invention is preferably produced by a process in which a cloth in the form of a continuous web having been subjected to raising treatment is immersed in water for removing fiber waste, dried, and cut.
The plush of the invention is preferably produced by a process comprising a step in which a cloth in the form of a continuous web is subjected to a set of raising treatments comprising a rough raising treatment and a fine raising treatment.
In the invention, the plush preferably is a light-shielding woven cloth having been subjected to raising treatment. When the cloth is a woven cloth, it preferably comprises a weft of two or three ply spun yarn or filament yarn. The woven cloth preferably comprises polyester fibers or polyamide fibers.
The invention also resides in a photographic film cartridge having a slit for drawing out a photographic film therethrough to which a light-shielding cloth is fitted, the light-shielding cloth having fiber waste of 30 pieces or less per 1 cm2 on its surface.